WO2006011239A1 - Capacitive mems device and process for fabricating same, and high-frequency device - Google Patents

Abstract

A capacitive MEMS device exhibiting good switching characteristics to high frequency signals, a process for fabricating the same, and a high-performance high-frequency device wherein such a capacitive MEMS device is mounted. The capacitive MEMS device comprises an upper electrode of a metal film moving up and down, and a conductor layer on a dielectric film formed on an opposing lower electrode. The area of a region where the conductor layer exists on the dielectric layer within the opposing region where the upper and lower electrodes face each other is not larger than the area of a region where the conductor layer does not exist on the dielectric layer within the opposing region.

Description

 4011219

Description Capacitance type M E M S element, manufacturing method thereof, and high frequency device Technical Field

 TECHNICAL FIELD The present invention relates to a capacitive type MEMS (Micro-Electro-Mechanical Systems) element and a manufacturing method thereof. Furthermore, another aspect of the present invention relates to a high-frequency device equipped with the capacitive MEM S element. Capacitance type MEMS elements are elements that turn on / off high-frequency electrical signals by changing the capacitance value. It is useful for high-frequency electrical signals from several megahertz to several terahertz. Background art

 Conventionally, the M E M S element is known as a fine electromechanical component that turns off electrical signals.

In particular, as a MEMS element applied to a high-frequency switch for turning on / off a high-frequency signal, for example, JJ Yao., TOPICAL REVIEW "RF MEMS fro a device perspective." J. Mi cromech. Mi croeng. 10 (2000) R9 -R38. (Especially R13, figure5) Capacitive (electrostatic drive) MEMS devices disclosed in (Reference 1), and HA C, Ti Imams., "RF-MEMS metal contact capaciti ve switches. ^{"4 th Round Tabl e on MINT} for Space. 20/22 may, 2003 (ESTEC, Noordwi jk, NL. Page4-Page7) is capacitive MEMS switch disclosed in (Reference 2). These have the function of changing the capacitance value between the upper and lower electrodes by the vertical movement of the upper electrode by voltage application.

'In the capacitive MEMS device shown in Reference 1, T JP2004 / 011219

 A thin dielectric film is formed on the signal line, which is a two-part electrode, and ground lines are formed in parallel on both sides of the signal line. The ground wire is electrically connected with a membrane composed of a metal anchor, spring, and upper electrode. This membrane is formed in such a way that a space is provided vertically across the dielectric film formed on the signal line.

 As a feature of the structure shown in Document 2, a metal film called a floating metal is formed on the dielectric film on the lower electrode located below the upper electrode.

 The basic operation of the element is as follows. In the above-mentioned two types of MEMS elements, when no DC voltage is applied between the membrane functioning as the upper electrode and the signal line as the lower electrode, it is between the membrane and the dielectric film formed on the signal line. Depending on the space, the switch operation is on (membrane up), and the input signal reaches the output terminal. When a DC voltage is applied, the membrane is attracted to the signal line side by the electrostatic force (that is, Coulomb force) generated by the potential difference between the membrane and the signal line, and elastically deforms and bends to the substrate side. For example, in the capacitive MEMS element of Reference 1, the upper electrode is in contact with the dielectric film on the signal line, while in the capacitive MEMS switch of Reference 2, the upper electrode is on the dielectric film. It will be in contact with the formed floating metal.

As a result, the capacitor structure including the membrane, the dielectric film, and the signal line is formed in both of the two structures, so that the switch operation is in the off (membrane down) state. In this state, the input signal cannot reach the output end. However, in the structure disclosed in Reference 2, the floating metal formed in close contact with the dielectric film 11219

 Due to the effect of 3, the capacitance value in the off state can be obtained in a stable and high value as compared with the structure of Reference 1. For this reason, the structure of Document 2 has a characteristic that a switching characteristic for a high-frequency signal is better than that of the element of Document IV.

 In addition, the M E M S element of the above-mentioned method is called a capacitive M E M S element (switch) as well as an electrostatic drive type M E M S element (switch) because of its operating principle. In the following description of the present specification, the elements having the plural names are the same unless otherwise specified.

 There are two types of M E M S switches: a series connection type switch that connects M E M S elements in series with the signal line, and a shunt type switch that is connected in parallel. In this specification, a shaver type will be described as an example unless otherwise specified. It goes without saying that the present invention can be used for any type of switch. Disclosure of the invention

 A main object of the present invention is to provide a capacitive M E M S element which can obtain a good and stable switching characteristic for a high-frequency signal and which operates at a low voltage, and a method for manufacturing the same. Furthermore, another object of the present invention is to provide a high-performance high-frequency device equipped with the capacitive M E M S element of the present invention.

 The main forms of the capacitive M E M S element of the present invention are as follows. An insulating substrate; a lower electrode formed on the insulating substrate; a dielectric layer formed on the lower electrode; a conductor layer formed on the dielectric layer; and an upper electrode. . The upper electrode faces the lower electrode and is disposed at least with a gap from the conductor layer on the dielectric layer, and contact with the conductor layer on the dielectric layer is controlled. The

And in this invention, the conductor layer on the said dielectric material layer is the said insulating group. 2004/011219

In a region where the upper electrode and the lower electrode face each other when viewed from the vertical direction of the plate, a conductor layer on the dielectric layer exists in a part of the facing area, and the upper electrode The area of the region where the conductor layer on the dielectric layer exists in the region where the electrode and the lower electrode face each other is the area of the region where the conductor layer on the dielectric layer does not exist in the opposite region, etc. It is important to be small or small.

 Furthermore, another form of the capacitive M E M S element of the present invention is as follows. An insulating substrate; a lower electrode formed on the insulating substrate; a dielectric layer formed on the lower electrode; a conductor layer formed on the dielectric layer; and an upper electrode. Have. The upper electrode is disposed so as to face the lower electrode and at least have a gap with the conductor layer on the dielectric layer, and contact / non-contact with the conductor layer on the dielectric layer is controlled. The It is important that the conductor layer on the dielectric layer is connected to a desired potential in a direct current manner through a resistor for high-frequency signals.

 Furthermore, another aspect of the present invention is to provide a high-frequency device having the various capacitance type M E M S elements. Brief Description of Drawings

 FIG. 1A is a plan view for explaining a first embodiment of a capacitor MEMS element according to the present invention.

 FIG. 1B is a sectional view taken along line BB ′ in FIG. 1A.

 FIG. 2A is a plan view for explaining another means for solving the problems of the prior art.

 FIG. 2B is a sectional view taken along line BB ′ in FIG. 2A.

FIG. 3A is a plan view for explaining a conventional capacitive MEMS element. FIG. 3B is a sectional view taken along line BB ′ in FIG. 3A. FIG. 4A is a top view for explaining a conventional capacitive MEMS element.

 Fig. 4B is a cross-sectional view taken along line 8-8 in Fig. 4. FIG. 5 is a plan view for explaining means for solving the problems of the prior art.

 FIG. 6 is a plan view for explaining another means for solving the problems of the prior art.

 FIG. 7A is a plan view for explaining the first embodiment of the capacitor M EMS element according to the present invention.

 Fig. 7B is a cross-sectional view taken along line 8-8 'in Fig. 7. FIG. 8 is a plan view for explaining a third embodiment of the present invention. FIG. 9A is a plan view for explaining a fourth embodiment of the capacitor MEMS element according to the present invention.

 FIG. 9B is a sectional view taken along line 8-8 ′ in FIG. FIG. 9C is a schematic perspective view for explaining the structure of the membrane in the example of FIG. 9A.

 FIG. 1 O A is a plan view for explaining a fifth embodiment of the capacitor M E M S element according to the present invention.

 FIG. 108 is a cross-sectional view taken along line BB ′ in FIG. FIG. 11A is an equivalent circuit diagram of the control circuit of the sixth embodiment. FIG. 11B is an equivalent circuit diagram of the control circuit of the seventh embodiment. FIG. 12A is a cross-sectional view showing the membrane in an up state in the sixth embodiment.

FIG. 12B is a cross-sectional view showing the membrane in a down state in the sixth embodiment. T JP2004 / 011219

 6 FIG. 13 is an equivalent circuit diagram for explaining the control circuit used in the eighth embodiment.

 FIG. 14 is a block diagram for explaining the ninth embodiment. FIG. 15 is a cross-sectional view showing an example of the manufacturing process of the capacitive M EMS element according to the first embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

<Consideration of problems>

 Prior to concrete description of various embodiments for carrying out the invention, the problems found by the inventors will be explained and discussed with respect to the conventional capacitive MEMS element.

 The inventors first made a prototype of a capacitive MEMS device having a structure substantially equivalent to that of Document 1, and evaluated the absolute value and the capacitance ratio of the capacitor during the switch operation (on / off) as described above. did.

 The prototype capacitive M E M S element at this time has the structure shown in Fig. 3A and Fig. 3B. FIG. 3A is a plan view of the element, and FIG. 3B is a sectional view. A signal line 1 is provided on the insulating substrate 3. Surround this with the ground wire

2 is arranged. A dielectric film 5 is formed so as to cover the signal line 1. An upper electrode 12 is provided while maintaining a gap 80 with the dielectric film 5 while being in contact with the ground wire 2. Panels 1 1 are formed at both ends of the upper electrode 12. Upper electrode 1 2, panel 1 1, and anchor 1 connected to panel

The member composed of 0 is called membrane 8.

Membrane 8 has an anchor 10 connected to a grounding wire 21 (hereinafter referred to as “earth”), a panel 11 1 having a meander (bending structure), and an upper electrode 12 having a body structure. . The signal line 1 and the upper electrode 12, which are lower electrodes formed in contact with the substrate (3) below the membrane 8, 04 011219

 7 The area of the opposing area (the area where both the upper and lower electrodes overlap when viewed from the vertical direction: hereinafter simply referred to as “opposing area” unless otherwise noted) is 2 0 0 micrometer X 2 0 0 It's a micro-meat.

 The distance of the space 80 between the upper electrode 12 / dielectric film 5 is about 1.3 micrometers, and a dielectric formed on a part of the lower electrode signal line 1 and part of the insulating substrate 3 As the material of the film 5, an alumina film having a film thickness of 0.3 micrometers was used.

 The membrane 8 is made of Au (gold) with a film thickness of 2.5 micrometers. On the other hand, the signal line 1 which is the lower electrode and the ground wire 2 connected to the membrane 8 are connected to the lower layer. A laminated film of an upper layer A u (gold, film thickness of 0.5 μm) with a thickness of 0.5 μm) was used.

 In the middle of the manufacturing process, a sacrificial layer pattern to be removed later is formed under the membrane to form a membrane 8 that floats in the air. In order to facilitate the removal of the sacrificial layer, although not shown, the upper electrode 2 is provided with a plurality of 10-micrometer hole holes at intervals of 20 micrometers. The sacrificial layer will be described later.

 As materials used for the sacrificial layer, there are generally a silicon oxide film, a photoresist film, a polyimide film, and the like, but a polyimide film was used for the production of the capacitive MEMS element.

Using the capacitive MEMS element with the above structure, the voltage applied to signal line 1 was gradually increased from 0 V (where earth 2 was grounded). As a result, upper electrode 1 connected to earth 2 2 / For the capacitance value (about 0.5 p F) obtained when no voltage is applied between the lower electrode 1 that is the signal line (0 V: membrane up), the upper electrode 1 2 Z lower Even if a DC voltage of 6 V is applied between the electrodes 1 and the upper electrode 1 2 is attracted in the direction of the lower electrode 1 and comes into contact with the dielectric film 5 (membrane down), the capacitance value 2004/011219

 8 increased only to about three times the value (about 1.6 pF).

 Regarding the operation of the capacitive MEMS element, in the calculation by simulation, the upper electrode 12 is completely in contact with the dielectric film 5 (membrane), so that the capacitance value is higher than when the membrane is up (ie, at 0 V). However, as described above, the increase in the capacitance value was extremely small in the actual prototype.

 As a result of investigating the cause, it was found that even when a voltage in which the upper electrode 12 was completely in contact with the dielectric film 5 was applied, a slight gap (air gap) was generated between them.

 That is, it is considered that the capacitance value is reduced due to the formation of a low dielectric region between the upper and lower electrodes due to the air gap.

 On the other hand, the structure disclosed in Document 2 was also prototyped, and the absolute value of capacitance and the capacitance ratio when a voltage similar to that described above was applied were evaluated.

 The prototype capacitive M E M S element at this time has the structure shown in Figs. 4A and 4B. FIG. 4A is a plan view of the element, and FIG. 4B is a cross-sectional view taken along line B B '.

 A signal line 1 serving as a lower electrode is provided on the insulating substrate 3. A grounding wire 2 is disposed around the signal line 1. In this example, a floating metal (a metal film in a flow 卜 state) 6 is disposed on the dielectric film 5. An upper electrode 12 is provided in contact with the ground line 2 while maintaining a gap 80 with the floating metal 6 and the dielectric film 5. In addition, the membrane 8 connected to the spring 11 and the panel is formed at both ends of the upper electrode 12. The membrane 8 is composed of an upper electrode 1 2, a spring 1 1, and an anchor 0.

In this example, the structure shown in FIGS. 3A and 3B is formed with a floating metal 6 that is not electrically connected to anywhere at all times. It is. In this example, the metal film 6 is an Au (gold) film having a thickness of 100 nm on the dielectric film 5 in the facing region 8 1.

 The area of the floating metal 6 was smaller than the opposing region 8 1 of the two electrodes, and the dimensions were 1800 micrometers × 180 micrometers. The positions formed are covered from the outer peripheral four sides of the opposing area 8 1 to the area inside 10 micrometers each.

 As a result of evaluation using the capacitive M E M S element having the above structure, the upper electrode 1

2 When a DC voltage is applied between the Z lower electrode 1 and the upper electrode 1 2 is attracted in the direction of the lower electrode 1 and brought into contact with the floating metal 6, the capacitance value is 2 4 p F (0 The capacitance value was extremely high (about 50 times that at V).

 However, an operating voltage of about 20 V, which is about 3 times higher than that without the floating metal 6, is required. Furthermore, after repeating the up-and-down movement of the membrane several times and leaving it to stand for several seconds while applying the voltage of 20 V, the capacitance value between the upper and lower electrodes becomes the initial value (0.

The phenomenon of returning to about 5 pF occurred.

 Furthermore, when the applied voltage is returned to 0 V from this state, the capacitance value is 2 0

There was also a mysterious phenomenon that increased to P F or more, but returned to the initial value (about 0.5 p F) after a few seconds.

 From the above, capacitive type M with the above-mentioned floating metal 6

It has been found that the EMS element requires a high voltage for the operation of the element and can provide extremely unstable switching characteristics, particularly when applied to a high-frequency switch that handles high-frequency signals of several hundred megahertz or more.

 <Consideration of Invention and Phenomenon>

As described above, the essence of the present invention is a capacitive MEMS element having a floating metal made of a conductor layer. The area ratio of the layer (floating metal) should be 50% or less of the entire opposing region (otherwise the dielectric film exposed region).

 Furthermore, another means for solving the above problem is to connect the conductor layer (floating metal) in a direct current manner with a substance having a desired potential through a substance that becomes a resistance to a high-frequency signal. . At this time, the substance that becomes a resistance to the high-frequency signal is a resistor that exhibits an electrical resistance value of at least〗 kΩ and less than 1 MΩ, and a high-frequency signal that is at least 1 ° <Ω or more. It is desirable that the inductor has an impedance of less than Ω.

 Depending on the structure of the element, the substance having the desired potential may be any of the group consisting of the upper electrode, a ground region (ground), and a control electrode that controls the vertical movement of the upper electrode by applying a DC voltage. It is also desirable to facilitate the device fabrication. In this way, it is fundamentally possible to prevent a tipping.

 The pattern shape of the floating metal is not particularly limited to a specific shape. For example, by providing an opening having a predetermined shape inside the pattern as long as the area ratio in the facing region is protected. The exposed region of the dielectric film may be secured.

 Further, it is desirable that the panel, the anchor, and the upper electrode have an integral structure and are formed of a continuous metal body.

The metal body is preferably formed of a substance mainly composed of at least a low-resistance metal material. For example, a single-layer film containing aluminum, a laminated film of an aluminum-containing film and another metal film, According to any one of a single-layer film containing gold, or a laminated film of a gold-containing film and another metal film, a single-layer film containing copper, or a laminated film of a copper-containing film and another metal film It is desirable that it be formed. T JP2004 / 011219

 11 For the conductor layer on the dielectric film, for example, a single-layer film containing aluminum, a laminated film of an aluminum-containing film and another metal film, a single-layer film containing gold, or a gold-containing film It is desirable that the film is formed of any one of a laminated film with another metal film, a single-layer film containing copper, or a laminated film of a copper-containing film and another metal film. That is, in general, it is preferably formed of a substance mainly composed of a low-resistance metal material.

 Considering the high voltage operation shown in the above prior art, first, the electrostatic force is greater than the restoring force of the panel to which the upper electrode is connected in order for the upper electrode to be attracted toward the lower electrode by electrostatic force. Must be.

 However, in the case where a floating metal is provided on the lower electrode via a dielectric film as in the above structure, the electrostatic force from the lower electrode in that region strongly acts on the floating metal (the floating metal is also connected to the upper electrode). Same potential: ie 0 V).

 As the DC voltage is continuously applied, electric charges are gradually accumulated in the floating metal, so that a potential difference between the floating metal and the upper electrode located on the floating metal starts to occur. And as the potential difference between them increases, the electrostatic force generated between them increases, and the upper electrode is attracted to the floating metal.

 At this time, voltage application starts until the electrostatic force generated between the floating metal and the upper electrode located on the floating metal accumulates the charge on the floating metal and can attract the upper electrode. There will be a slight time difference from

For this reason, only a very weak electrostatic force is generated in the wide opposing region between the floating metal and the upper electrode immediately after voltage application. 12 For example, in order to move the upper electrode up and down by performing a voltage switching operation in a short time of 1 second or less, the electrostatic force of the entire opposing area including the wide area that generates weak electrostatic force In order to be larger than this, it must be attracted mainly in the narrow area of the outer periphery where there is no floating metal (generation of strong electrostatic force). At this time, a weak electrostatic force is also generated in the floating metal region. As a result, a voltage higher than that of the structure without the floating metal is required, and it is considered that a voltage as high as 20 V is required for the operation of the element having the conventional structure.

 Next, the mysterious phenomenon related to the behavior of the capacitance value according to the present invention will be considered.

 As described above, when a DC voltage of 20 V is applied between the upper electrode and the lower electrode, and the upper electrode comes into direct contact with the floating metal, the upper electrode starts to accumulate charges like the floating metal. The

 By continuing to apply the DC voltage as described above, the upper electrode and the floating metal have the same potential, and the electrostatic force generated from the floating metal to the upper electrode disappears. As a result, the electrostatic force that attracted the upper electrode was smaller than the restoring force of the panel, and the upper electrode moved away from the floating metal, resulting in a smaller capacitance value. At this time, since the floating metal is electrically insulated, the accumulated charge is released only by spontaneous discharge. And natural discharge takes tens of seconds.

If the applied voltage is suddenly reduced to 0 V while the charge is stored in the floating metal, the upper electrode, which was originally grounded to ground and returned to 0 V, is connected to the floating metal that has been stored with charge. Between 04011219

 In addition, since a large potential difference is generated, an electrostatic force larger than the restoring force of the spring is generated during this time, and the upper electrode is attracted to the floating metal and comes into contact with it, and the capacitance value is temporarily recovered. .

 However, since the electric charge accumulated in the floating metal is quickly released through the upper electrode, the potential of the floating metal returns to 0 V after a few seconds, the electrostatic force disappears, and the restoring force of the panel separates them. It is probable that the capacitance value has returned to the initial value.

 In order to confirm the above consideration, first, using a capacitive MEMS element having the same dimensions and structure as the example illustrated in FIGS. 4A and 4B, the floating metal region and the capacitance in the opposite region It was fabricated by changing the area ratio with respect to the film region, and each operating voltage and the presence or absence of the above phenomenon were examined.

The size of the facing region between the upper electrode and the lower electrode of the capacitive MEMS element used in this experiment is 2 0 0 micrometer x 2 0 0 micrometer as described above, and the dimensions of the floating metal are 1 0 0 respectively. Microphone mouth (25% of the total), 120 micrometer port (36% of the total), 1550 micrometer port (56% of the total), 1700 micrometer ^α (total 7 2% of the body). The formed position was formed so that the center of the facing region and the center of the floating metal were aligned.

Each of the devices was evaluated five by one, and the results are summarized in Table 1.

table 1

 Size Area ratio Operating voltage Change in capacitance

(Ac mD)%) Γ) Number of occurrences (5)

1 0 0 2 5 7. 2 0

 1 2 0 3 6 8. 1 0

 1 4 0 5 0 8. 7 0

 1 5 0 5 6 9. 0 1

 1 7 0 7 2 1 6. 4 5 From Table 1, regarding the operating voltage, the smaller the floating metal, the lower the operating voltage. With an element with a floating metal of 1550 micrometers □ (5 6% of the total), the operating voltage without floating metal (= 6 V, approximately 1.5 times that of the prior art) is 9 V. I found it to work. The 14 1 micrometer (50% of the total) element operates at 8.7 V.

 Next, regarding the inexplicable behavior (change) of the capacitance value that occurs when the DC voltage is left as it is applied, the area ratio dependence of the floating metal in the total facing area clearly appears. The size of the floating metal is about 56% of the total facing area. 1 5 0 Micrometer Overnight When the ratio is large at the border ^, all mysterious capacity changes have occurred, and conversely it is smaller. In all cases, the results did not occur.

The element with 1 50 micrometer □ floating metal shows the behavior of changing the capacitance by 1 (/ 5), while the element with〗 4〗 micrometer □ floating metal has a mysterious capacitance change. Does not occur. Therefore, the area of floating metal that can actually be applied 19

 15 It can be said that the ratio is preferably 50% or less of the entire opposite area. As an application, an element with the structure shown in Fig. 5 was created and evaluated. The structure of FIG. 5 is substantially the same as the structure of FIG. 4A, except that the floating metal 6 is formed on the dielectric film 5 outside the opposing region from the floating metal 6 formed in the opposing region. It is also formed as a continuous series of patterns. At this time, the area ratio of the floating metal in the facing region viewed from the vertical direction is about 45% of the entire facing region.

 As a result, the operating voltage was 9.8 V, and it did not show a mysterious capacitance value behavior due to the voltage application. Furthermore, the capacitance value was about 45 pF, which was about 90 times the initial value (0.5 pF).

 This is because when the upper electrode 12 is in electrical contact with the floating metal 6, the floating metal 6 having a large area formed on the dielectric film 5 on the lower electrode 1 is opposed to the opposing lower electrode. It can be estimated that the facing area between and 1 is reflected in the capacitance value. Floating metal placement like this structure is an excellent way to increase the on / off capacitance ratio of the switch.

From the results of the above applied experiments, it has been found that the defects caused in the conventional technology can be avoided by setting the area ratio of the floating metal in the facing region within the specified range (50% or less). did. In addition, the floating metal pattern layout like this structure does not adversely affect the electrostatic force acting between the upper and lower electrodes, and is one excellent way to increase the switch on-off capacitance ratio. It can be said that this is a technique. In other words, if the area ratio of the floating metal in the opposite region is 50% or less, the relationship of electrostatic force> panel restoring force can be maintained even when charge is accumulated in the floating metal. 04 011219

 16 In the experiments described above, in order to make it easy to compare the obtained results, all the same structure and the same size of the shunt-type capacitive MEMS element are used. Even when an experiment was conducted using a capacitive MEMS element with a different structure, and changing the area ratio of the floating metal, the same results were obtained.

 However, if the reasoning is correct, the charge in the floating metal always remains accumulated, so there is a possibility that the operation of the element becomes unstable when the operation is repeated continuously.

 Therefore, a resistor pattern 7 having an electrical resistance value of 1 kΩ or more (3.7 kΩ in actual measurement) is arranged between the floating metal 6 and the case 2 of the element shown in FIG. A capacitive MEMS device with the structure shown in the figure was fabricated. In the same way as in the previous examples, a DC voltage was applied between the upper and lower Z electrodes, and the presence or absence of changes in the capacitance value due to leaving the operating voltage and the operating voltage applied was evaluated. In addition, although it is a method for determining the resistance value of the resistor, the capacitive MEMS element is mainly used as a switch for a high-frequency signal, and has a relatively high resistance as a property of the high-frequency signal. Since it is not possible to pass through a substance or an inductor that has high impedance as an impedance, in this experiment, the metal resistor of 1 Ω or more was used as an example.

The existence of the resistor is one of the methods for quickly releasing the electric charge that is considered to be accumulated in the floating metal. As an example, in this structure, the connection destination of the floating metal is grounded. As a result, the floating metal is short-circuited in terms of direct current, but remains floating in terms of high-frequency. As a result, although the operating voltage itself was increased to 15 V, the inexplicable behavior of the capacitance value was not observed when the voltage was left applied. Furthermore, 9

 17 It was confirmed that even when the applied voltage was returned to 0 V, the capacitance value remained at the initial value and did not change.

 Regarding the above results, regarding the increase in operating voltage, in the case of the above structure, the upper electrode connected to the ground and the floating metal connected via the resistor are always at the same potential in terms of DC. Therefore, no electrostatic force is generated between the floating metal and the upper electrode, and only in the narrow facing area between the lower electrode under the dielectric film exposure area other than the floating metal and the upper electrode in the area facing it. It can be estimated that this is because they are attracting each other.

 The reason why the capacitance value does not change in the neglected state due to voltage application is that it is attracted only in the narrow region where charge accumulation does not occur, and the upper electrode is pulled to the floating metal by returning to 0 V. The reason why it cannot be attached is presumed that the charge accumulated in the floating metal was released quickly by connecting the floating metal and ground via a resistor.

 From the above detailed experiments and considerations, it was found that the charge accumulation of the floating metal can be prevented by connecting a resistance element between the floating metal and the ground (or voltage terminal).

 However, depending on the resistance value of the resistance element as described above, the switching time / loss (On / Offf) switching time and loss of the switch deteriorate. When a resistive element is used to release charge from floating metal to ground, the amount of charge remaining on the floating metal is inversely proportional to the exponential function of time.

The time constant dt at which the amount of charge is 1 / e (e is 2.7 1 8 2 8) is the product of the capacitance C f of the floating metal and the ground C f, and the resistance value R f of the resistive element used C f · Represented by R f. Since the time constant dt must be smaller than the required on / off switching time dt 0 ff, dt 0 ff >> dt Need to be. In the case of a low-loss switch operating in the GHz band, C f needs to be 5 p F to 20 p F and dtoff <0.1 msec, so that R f <5 R to 20 MΩ There is a need.

 When designing the switch loss, it is necessary to consider the balance with the Q value of the electronic components (and filters, etc.) connected to the switch. However, the Q value of the filter is about 20 to 200, and especially in the case of a high Q filter, the switch is required to have high performance.

 A typical dielectric, S AW filter, has a Q value of 800 or more and a series resistance of 1 Ω or less. Therefore, R f> 8 0 0 Q (= 1 Ω Χ 8 0 0) is there.

 In the above description, the floating metal is connected to the ground. However, the same effect can be obtained when the voltage terminal is used. In addition, when an inductor is used to change the resistance element, the same effect can be obtained by replacing it with impedance in the frequency band in which R f is operated.

Next, aiming at low voltage operation of the switch by the resistor connection structure, the area ratio of the floating metal in the opposing region is adjusted, and the capacitive MEMS element having a structure in which the floating metal is arranged outside the opposing region. And the operating voltage was evaluated. Examples of this are shown in FIGS. 2A and 2B. Fig. 2A is a plan view and Fig. 2B is a cross-sectional view along line BB. This example differs from the example in Fig. 6 in the shape and area ratio of the floating metal 6. Therefore, other detailed explanation is omitted. In this example, the area ratio of the floating metal 6 was designed to be 5% of the entire facing area. In short, the area of the floating metal 6 in the opposing region is remarkably reduced, and the floating metal 6 is extended and formed on the dielectric film 5 other than the opposing region. Furthermore, floating metal 6 is short-circuited to ground 2 through a resistance element of about 2 kΩ. It is the structure made to do.

 As a result, the operating voltage was 6.2 V. This voltage value is almost the same value as when no floating metal was provided, and the capacitance value obtained at this time was 3 2 p F, which was approximately 60 times the initial value.

 From the above, in order to solve the problem of the capacitive MEM S element generated in the prior art, it can be achieved by using at least one of the following items. Of course, both can be used in combination.

 (1) In the structure having the conventional floating metal, the area ratio of the floating metal in the opposing region

5 Set to 0% or less.

 (2) The floating metal itself is connected in direct current to a substance having a desired potential via a substance that becomes a resistance to a high-frequency signal.

 Preferably, if the area ratio of the floating metal in the opposing region is significantly reduced, for example, around 15% of the total, the capacitive M E M that operates at an operating voltage almost equivalent to the structure without the floating metal

S element can be manufactured.

 Furthermore, even if the formation region of the floating metal is expanded on the dielectric film on the lower electrode other than the opposing region, the floating metal can be used as long as the restrictions on the area ratio of the formation pattern in the opposing region are observed. You may form widely also in area | regions other than an opposing area | region. This is because the floating metal formation region has no effect on the electrostatic force generated in the opposing region. As a result, the capacitance value during operation and the on / off capacitance ratio can be increased.

Further, the shape of the floating metal in the facing region is not particularly limited, and may be provided in any shape. 19

 20 The substance that becomes a resistance to the high-frequency signal is, for example, a high-resistance body having an electrical resistance value of 1 to 1 MΩ or an inductor that exhibits an impedance of 1 to 1 MΩ. The substance having a desired potential refers to, for example, a ground wire, an upper electrode, a lower electrode, a control electrode, etc., depending on the structure of the element.

 Further, it is desirable that the anchor, the panel, and the upper electrode form an integral structure to form a membrane and be formed of a continuous and same low-resistance metal body.

 At this time, the metal body is preferably a single metal film having a low resistance of gold, aluminum, or copper, or a laminated film of the metal species and another metal.

 The low-resistance metal film formed on the dielectric film is also preferably made of a low-resistance metal material, and in particular, a material that can significantly reduce the contact resistance with the upper electrode is preferable. Specifically, it is desirable to be a single metal film such as gold, aluminum, or copper, or a laminated film of the above metal species and another metal.

 Further, the surface of the floating metal made of the low-resistance metal film is the same material as the floating metal, or other materials unless the surface of the floating metal is in contact with the upper electrode at a constant time (when no voltage is applied), except for a flat surface. One or a plurality of upward projections made of a low-resistance metal material may be provided.

 On the contrary, if the above condition is satisfied, it goes without saying that the same effect can be obtained even if one or a plurality of protrusions directed downward are provided on the lower surface of the upper electrode.

As described above in detail, according to the present invention, extremely good and stable switching characteristics and isolation characteristics can be obtained for high-frequency signals. It is. Furthermore, according to the present invention, it is possible to provide a capacitive MEMS element that operates at a low voltage with high reliability, and a high-performance high-frequency device equipped with the capacitive MEMS element of the present invention.

 In the capacitive MEMS element of the present invention, for example, the capacitance value at the time of switching off (when applying voltage) when functioning as a high-frequency switch is also used to extend the floating metal on the dielectric film located on the lower electrode other than the opposing region. In addition to being able to be made large by forming it long, the capacitance value almost as calculated can be easily realized from the area of the entire floating metal, so the design of the switch element becomes extremely easy.

 Furthermore, as described above, the floating metal formation area can be expanded to areas other than the opposing area, and the upper electrode only needs to be in contact with the floating metal at one location. Can be small. As a result, the bending / deformation due to the residual internal stress of the membrane including the upper electrode made of a metal body may be remarkably suppressed.

 Floating metal made of a low-resistance metal film in contact with the upper electrode is also extremely low because the contact resistance and series resistance can be reduced by using a metal film mainly composed of Au, AI, and Cu with low resistance. High frequency signals can be transmitted without loss.

 Due to the structure and properties of the capacitive MEMS element of the present invention, in addition to its use as a high-frequency switch, one or more of these elements can be connected in parallel and in series, so that an SP n T switch, It can also be applied to variable capacitance devices that can vary a wide range of capacitance values.

Furthermore, since the capacitive MEMS element of the present invention requires a very slight increase in process from the viewpoint of the manufacturing process, an increase in manufacturing cost can be suppressed to a small extent. Since the capacitive MEMS element of the present invention can be easily manufactured by a general semiconductor manufacturing process, it is formed on the same substrate as a semiconductor active device such as an FET or a bipolar transistor and other passive devices. Therefore, it is possible to easily manufacture a module device that is smaller than before.

<Embodiments>

 Hereinafter, the capacitive M E M S element according to the present invention will be described in more detail with reference to some preferred embodiments shown in the drawings.

 1A and 1B schematically show a first embodiment of the present invention. FIG. 1A is a plan view of the element, and FIG. 1B is a cross-sectional view along the line B B '. A signal line 1 that also functions as a lower electrode of the element is formed on an insulating substrate 3, and a ground 2 is formed around it. The insulating substrate 3 is formed of an insulating material such as a glass substrate, a compound semiconductor substrate, a high-resistance silicon substrate, or a piezoelectric substrate. The insulating substrate 3 may be a semi-insulating substrate whose surface is covered with an insulating film typified by silicon oxide, or a conductive substrate.

 The signal line 1 functions as a coplanar type high-frequency signal line extending in the front and back direction of Fig. 1B, together with the ground 2 installed at a predetermined distance.

 The membrane 8 formed so as to straddle the signal line 1 from the ground 2 is composed of four springs 1 having four anchors 10 connected to the ground 2 and meanders (bending structure) connected to the anchor 10. 1 and the upper electrode 1 2 form a body structure.

A part on the signal line 及 び and a part on the insulating substrate 3 are covered with a dielectric film 5 made of an alumina film having a film thickness of 0.2 micrometer and located on the signal line 1. The surface of the dielectric film 5 has a T i ZA u two-layer structure. A floating metal 6 made of a low resistance metal film is formed. The area ratio of the floating metal 6 in the opposing region between the signal line 1 and the upper electrode 8 is 15% of the entire opposing region, and the dielectric located on the signal line 1 outside the opposing region On the film 5, the floating metal 6 is extended and formed widely. Floating metal 6 is grounded through resistance element 7 with an electrical resistance of 15 kΩ.

Connected to 2.

 In addition to being grounded at high frequency, Earth 2 is also grounded (DC potential 0 V) in DC. Therefore, the upper electrode 12 is grounded via the spring 11 and the anchor 10. However, since the floating metal 6 is connected to the ground 2 through the resistance element 7, it is grounded only in a direct current manner.

 The distance of the space between the upper electrode 12 and the dielectric film 5 is about 1.2 micrometers.

 The membrane 8 is made of Au (gold) with a film thickness of 2.5 micrometers, and the signal line 1 and the ground line 2 are connected to the lower layer T i (film thickness = 0.05 micrometer). The upper layer A u (gold, film thickness 0.5 micrometer) is used.

A polyimide film is used as a sacrificial layer for forming the membrane 8 that floats in the air. In order to facilitate the removal of the sacrificial layer, although not shown, the upper electrode 12 is provided with a plurality of through holes of 10 micrometers ⁰ at intervals of 20 micrometers.

The operating voltage (voltage at which the upper electrode contacts the low-resistance metal film) of the MEMS element having the above structure was 6.3 V, and the capacitance value at that time was about 48 pF. This is a value that is about 100 times closer to 0 V compared to about 0.5 p F. This value is the opposite of floating metal 6 and signal line〗 A capacitance value almost the same as the value calculated from the area was obtained. FIG. 7A and FIG. 7B schematically show the second embodiment of the present invention. In this example, the present invention is applied to a capacitive MEMS element having a structure using a cantilever made of a metal body. FIG. 7A is a plan view of the element, and FIG. 7B is a sectional view taken along the line BB ′.

 A signal line 13 having a function as a lower electrode of the element is formed on a glass substrate 5 whose surface is covered with silicon oxide, and a ground wire 4 is formed around the signal line 13.

 The cantilever beam 1 6 formed so as to cover a part of the signal line 1 3 from the ground pole 4 is composed of an anchor 1 7 connected to the ground 1 4 and a panel 1 8 connected to the anchor 1 7. The upper electrode 19 has a body structure. The area of the upper electrode 19 is 20 micrometers to 50 micrometers.

 Part of the signal line 1 3 and part of the Si substrate 15 are covered with a dielectric film 20 made of a silicon nitride film having a thickness of 0.15 micrometers. A floating metal 21 made of AI is formed on the surface of the dielectric film 20 located above.

 At this time, the area ratio of the floating metal 21 in the opposing region between the signal line 13 and the upper electrode 9 is 10% of the entire opposing region, and the signal line 1 outside the opposing region is Also on the dielectric film 20 located on 3, the floating metal 2 1 is extended and widely formed. The floating metal 2 1 is connected to the ground 14 through a resistance element 2 2 having an electric resistance value of 500 kΩ.

In addition to being grounded at high frequency, ground 14 is also grounded (DC potential 0 V), so the upper electrode 19 connected to ground 14 is also grounded. . But floating metal PT / JP2004 / 011219

 twenty five

 Since 2 1 is connected to ground 7 through resistance element 2 2, it is grounded only in a direct current manner. The distance of the space between the upper electrode 19 and the dielectric film 20 is about 0.8 micrometers.

 The cantilever 16 as a whole is made of AI (aluminum) with a thickness of 2.0 micrometers, and the signal line 1 3 and ground 14 are also AI (aluminum, thickness 0). 4 micrometer) A single membrane is used.

 The sacrificial layer used to form the cantilever 16 having the upper electrode 19 that is connected to the earth 14 and floated in the hollow is made of a photoresist film. In order to facilitate the removal of the sacrificial layer, Although not shown, the upper electrode 19 is provided with a plurality of through-holes of a 2-micrometer meter opening at intervals of 5 micrometers.

 The operating voltage (voltage at which the upper electrode contacts the low-resistance metal film) of the M E M S element having the above structure was 1.5 V, and the capacitance value at that time was about 24 pF. This is a value of about 120 times the capacitance value at 0 V compared with about 0.2 pF.

 Since the area of the upper electrode 19 in the second embodiment is significantly smaller than that in the first embodiment, the overall size of the device is also smaller than that in the first embodiment.

 However, the operating voltage was lowered to 1.5 V, and the obtained capacitance value was almost the same as that of the first embodiment. Thus, by applying the structure of the present invention, it is possible to manufacture a high-capacity capacitive MEMS element having a smaller size and superior switching characteristics.

As a third embodiment of the present invention, an example of a capacitive MEMS element in which a control terminal is provided separately from a signal line and ground will be described. An example of this is shown in the plan view of Figure 8. A signal line 6 1 is formed on a glass substrate 60, and a ground 6 2 is formed around the signal line 61. A control terminal 6 that is not electrically connected to the ground 6 2 in part of the ground 6 2 region. 3 is formed.

 Membrane 64 has an electrostatic force between anchor 65 connected to control terminal 63, panel 6 6 having meander (bent structure) connected to anchor 65, and ground 62. The upper electrode 6 7 formed by the existence of the region 6 7-1 for generating and the region 6 7-2 in contact with the floating metal 70 forms a body structure. .

 The anchors 65 are formed at four locations, but only one anchor is connected to the control terminal 63, and all other anchors are formed on the glass substrate 60.

 Part of the signal line 6 1, part of the glass substrate 60, and part of the ground 6 2 were covered with a dielectric film 6 9 made of oxide oxide and having a thickness of 25 50 nanometers. A floating metal 70 is formed on the dielectric film 69 located on the signal line 61. The floating metal 70 is connected to the signal line 61 through an inductor element 71 having an impedance characteristic of about 150 kΩ for a high frequency signal of about 1 GHz. The signal line 6 1, the earth 6 2, the control terminal 6 3, the membrane 6 4, and the floating metal 70 are all made of copper.

 In the above structure, there are only a few regions where the dielectric film 69 is exposed in the opposing region between the upper electrode 67 and the signal line 61, and the area ratio occupied by the floating metal 70 is about 9%. 0%. However, since the electrostatic force between the membrane 6 4 and the earth 6 2 is mainly generated, there is no problem in operation.

The structure described above is based on the floating mem Inductor element 7 1 is provided in order to prevent charge accumulation in Tal 70.

 Since floating metal can be formed in almost all regions on the dielectric film on the signal line, the capacitance value obtained when the membrane contacts the floating metal by applying voltage to the control terminal has the feature that it can be remarkably increased.

 As described above, the Shank connection type element has been described as an example, but the present invention has the same effect even in the series connection type.

 FIG. 9A, FIG. 9B, and FIG. 9C schematically show the fourth embodiment of the present invention. Fig. 9A is a plan view of the device, and Fig. 9B is a cross-sectional view along line B B '. This figure shows a capacitive M E M S element with a seesaw structure membrane. FIG. 9C is a schematic perspective view illustrating the structure of the membrane.

 An input signal line 24 made of Cu (copper) with a film thickness of 500 nm is formed on a glass substrate 28, and output signal lines 2 5 (left side) and 2 6 (right side) are formed on both sides thereof. ) Is formed. Around that area, a ground 27 is formed.

 A membrane 29 made of A u connected to an input signal line 24 formed on a glass substrate 28 is a first torsion spring that connects two anchors 30 and the two anchors 30 in a hollow state. One spring 3 1, a second spring 3 2 extending from the first spring 3 1 to the left and right sides, and a second spring 3 2 connected to the left and right sides ), And 3 4 (right side of the figure).

Here, the input signal line 24 is connected to the left and right upper electrodes 33 and 34, and on the glass substrate 28 located below the upper electrodes, from the lower electrode Cu to the lower electrode. Output signal lines 2 5 (left side of the figure) and 2 6 (Right side of the figure), dielectric film 35 made of nitride nitride film, and floating metal 3 6 (left side) and 3 7 (right side) made of Ti / Au laminated film from below The upper electrode is formed on the left and right sides with a space of distance = 1.0 micrometer with respect to the upper electrodes.

 At this time, the area ratio of the left and right floating metals 3 6 and 3 7 in the area facing the left and right output signal lines 25 and 26 and the left and right upper electrodes 3 3 and 3 4 is Both of them are 35% of the entire opposing region, and floating metal 3 6 and 3 7 are also formed on the dielectric film 35 located on the output signal lines 25 and 26 outside the opposing region. Each is extended and formed widely.

 Floating metals 3 6 and 3 7 are connected to ground 2 7 through inductor elements 3 8 and 3 9 that exhibit an impedance of about 30 O k Q for high-frequency signals of about 1 GHz to 5 GHz. ing.

 The capacitive MEMS element having the above structure operates by applying a DC voltage between the input signal line 24 and either one of the output signal lines 25 and 26 arranged on the left and right.

 For example, when a voltage is applied to the left output signal line 25, the upper electrode 3 3 on the left is attracted to the line 25 and comes into contact with the floating metal 36 on the left, thereby forming a capacitor structure. . At this time, the high-frequency signal input to the input signal line 24 is output from the left output signal line 25 through this capacitor. At this time, the upper electrode 34 on the opposite side rises upward, so that the isolation between the output signal line 26 and the upper electrode 34 increases.

Conversely, by stopping the voltage application on the left side and applying a voltage to the output signal line 26 on the right side, the upper electrode 3 3 on the left side can be moved away from the low resistance metal film 36. Return. And the upper electrode 3 4 on the right side By being attracted to the output signal line 26 and coming into contact with the floating metal 37 on the right side, a high frequency signal is now output from the output signal line 26 on the right side. At this time, since the upper electrode 33 on the opposite side springs up, the isolation between the output signal line 25 and the upper electrode 33 increases.

 According to the above embodiment, the capacitive M E M S element of the basic invention generally has a structure called S P D T switch that can selectively switch between two paths for one signal line. This example reflects the effect of the present invention, and can provide a push-pull type 1-input 2-output switching switch for high-frequency signals having low loss and excellent isolation characteristics.

 In the capacitive MEMS element of the present invention, the case where an inductor element and a resistance element are provided inside the element has been described. Alternatively, a floating metal may be connected to a resistance element or inductor element formed outside the element. Similar effects can be obtained.

 A fifth embodiment of the present invention is schematically shown in FIG. 10A and FIG. 10B. FIG. 10A is a plan view of the element, and FIG. 10B is a cross-sectional view along the line B B '. The present example is an example in which the present invention is applied to an ONONIS switch having a series connection type, although it has a membrane having substantially the same structure as that described in the first embodiment. In the series connection type, the signal line is divided into the input side and the output side, a voltage is applied between the input side and the output side, and the high frequency signal is generated when the membrane contacts the low resistance metal film. It has a mechanism that flows to the output side.

An AI input signal line 40 is formed on the Si substrate 43 whose surface is covered with silicon oxide, and has a predetermined interval inside the U-shaped region of the line 40. Thus, an output signal line 4 1 made of AI is formed. And there is a ground 42 around it. The membrane 4 4 connected to the U-shaped region of the input signal line 40 and straddling the output signal line 4 1 is composed of four anchors 4 5 and meanders (folds) connected to the anchors 4 5. The four panels 46 6 having the structure) and the upper electrode 47 have a body structure. Part of the output signal line 41 and part of the Si substrate 43 are covered with a dielectric film 48 made of a tantalum oxide film, and the dielectric film 4 located on the output signal line 41 On the surface of 8, a floating metal 49 having an opening made of Au is formed. On the lower surface of the upper electrode 47, a plurality of protrusions 50 made of Au are formed downward.

 At this time, the area ratio of the floating metal 49 in the opposing region of the output signal line 4 1 and the upper electrode 47 is 15% of the entire opposing region, and the output signal line 4 outside the opposing region is 1 Floating metal 49 extending from the opposing region is also widely formed on the dielectric film 48 located above

 The distance of the space between the upper electrode 47 and the floating metal 49 is about 1.0 micrometer, and the protrusion 50 provided on the lower surface of the upper electrode 47 has a height of about 0.3 micrometer. Therefore, the distance from the tip of the protrusion 50 to the floating metal 49 is 0.7 micrometers.

 The membrane 4 4 is made of Cu (copper) with a thickness of 1.5 μm, and the input signal line 40, the output signal line 4 1, and the ground 4 2 have AI ( A single film with a thickness of 0.6 micrometers) is used.

A photosensitive polyimide film is used for the sacrificial layer to form a membrane that floats in the hollow. The sacrificial layer is removed by wet stripping using a special stripper and carbon dioxide as the final step. A quick drying process was applied. 19

 31 In the MEMS element having the above structure, the upper electrode 4 7 connected to the input signal line 40 is connected to the output signal line by applying a voltage between the input signal line 40 and the output signal line 41. A capacitor structure is formed by being attracted to the line 4 1 and in contact with the low-resistance metal film 49. At this time, the high-frequency signal input to the input signal line 40 flows to the output signal line 41 through this capacitor.

 In the above embodiment, a resistance element or the like for discharging the charge accumulated in the floating metal is not provided. However, since the area ratio of the floating metal in the opposite region is as small as 15%, what is necessary for the element operation? It operates normally as a switch without causing any trouble.

 According to the embodiment, it is possible to provide a capacitive M E M S element for a high-frequency signal having a very small loss (loss) of an input signal and good pass characteristics.

 A high frequency device according to a sixth embodiment will be described. FIG. 11A shows a capacitive MEMS element according to the present invention described in the first embodiment as a high-frequency device equipped with a capacitive MES element according to the present invention. FIG. 7 is an equivalent circuit diagram of the MEMS element and the control circuit when applying (shown in FIG. B). A signal line 1 and an upper electrode 12 of the M E M S element are shown in a circuit form. FIGS. 12A and 12B are cross-sectional views of the MEMS element showing the up-down state of each membrane in this example. Each part in the cross-sectional view is indicated by the same reference numeral as that in the first embodiment.

The upper electrode 12 of the MEMS element functions as the high-frequency switch 52 of the present invention connected in parallel to the signal line 1. Reference numerals 5 3 and 5 4 denote an input terminal and an output terminal for the signal line 1, respectively. The signal line 1, which is the lower electrode, floats in a DC manner, and the control terminal 5 5 is connected to the signal line 1 through an inductance L and a resistance R that exhibit high impedance to high frequencies. Is connected. That is, when a control DC voltage is applied to the control terminal 55, the DC voltage is applied to the signal line 1 via the inductance L and the resistance R.

 When no DC voltage is applied to the signal line 1 (DC potential 0 V), the upper electrode 12 is mechanically held by the panel 11 as shown in FIG. 12A. Therefore, since the upper electrode 12 is sufficiently away from the signal line 1, the capacitance value between the upper electrode 12 and the signal line 1 is very small (membrane up, capacitance value is about 0.5 pF). At this time, the high-frequency signal flowing in the signal line 1 is transmitted from the input terminal 53 to the output terminal 54 with low loss (switch-on state).

 When a DC voltage is applied to the signal line 1, an electrostatic force is generated between the upper electrode 12 and the signal line 1. When the electrostatic force is stronger than the restoring force of the panel, the upper electrode 1 2 is in contact with the floating metal 6 formed on the dielectric film 5 as shown in Fig. 1 2 B (Membrane, Capacitance value = approx. 48 p F) (switch-off state).

 In this switch-off state, the upper electrode 12 is in electrical contact with the floating metal 6, and therefore consists of the floating metal 6, the dielectric film 5 and the signal line 1 connected via the upper electrode 12. It constitutes a capacity evening. As a result, at high frequencies, signal line 1 is equivalent to being grounded. Therefore, most of the high-frequency signal flowing from the input terminal 5 3 to the signal line 1 is reflected at the portion where the floating metal 6 in contact with the upper electrode 12 2 is in contact with the dielectric film 5. Almost no reach.

Since the electrostatic force between the upper electrode 12 and the signal line 1 is continuously held by the region 14, the capacitance structure is maintained unless the voltage application is stopped. P2004 / 011219

 33 A high-frequency device according to the seventh embodiment will be described. FIG. 11B shows a capacitive MEMS element having the series connection type according to the present invention described in the fifth embodiment (shown in FIG. 1 OA and FIG. 10B) similar to the above switch. The equivalent circuit diagram of the MEMS element and the control circuit when applied to is shown. An input signal line 40 and an output signal line 41 are shown in circuit form. Reference numerals 7 3, 7 4, and 7 5 indicate an input terminal, an output terminal, and a control terminal, respectively.

 The upper electrode 47 connected to the input signal line 40 functions as the high-frequency switch 72 of the present invention connected in series to the output signal line 41. Here, the output signal line 41 is connected to the control terminal 75 via an inductance L and a resistance R that exhibit high impedance to high frequencies. That is, when a control DC voltage is applied to the control terminal 75, the DC voltage is applied to the output signal line 4 1 via the inductance L and the resistance R. When no DC voltage is applied to the output signal line 4 1 (DC potential 0 V), the upper electrode 4 7 is sufficiently away from the output signal line 4 1, so the input signal is the output signal line 4 1 Not reach. (Membrane up) When a DC voltage is applied to the output signal line 41, an electrostatic force is generated between the upper electrode 47 and the output signal line 41. At this time, the upper electrode 4 7 is attracted and comes into contact with the floating metal 4 9 (membrane), so that the floating metal 4 9 and the dielectric film 4 8 connected via the upper electrode 4 7 and the output signal are connected. A capacitor consisting of line 4 1 is constructed. As a result, the input signal can reach the output signal line 4 1.

According to this embodiment, the high frequency switch equipped with the capacitive MEMS element of the present invention can obtain extremely good switching characteristics for high frequency signals. A high-frequency device according to the eighth embodiment will be described. As a high-frequency device mounted with the capacitive MEMS element of the present invention, the capacitive MEMS element of the present invention described in the fourth embodiment (switching that can switch one input signal to two paths) ( This is an example of applying Fig. 9A and Fig. 9B). Figure 13 shows an equivalent circuit diagram of the MEMS element and control circuit. The same reference numerals in FIG. 13 are used for the same parts as those in FIGS. 9A and 9B. Reference numeral 24 denotes an input signal line, and reference numerals 25 and 26 denote a left output signal line and a right output signal line, respectively. Reference numeral 2 9 is a membrane, 3 3 and 3 4 are left upper electrodes, right upper electrodes, 5 6 are input terminals, 5 7 and 5 8 are output terminals, and 5 9 is a control terminal.

 In the present embodiment, the membrane 29 is not connected to the ground but is connected to the input terminal 56 via the input signal line 24. Then, the upper electrode 33 on the left side of the membrane 29 is connected to the output signal line 25 at a high frequency and connected to the output terminal 57, or the upper electrode 34 on the right side is connected to the output signal line 26. Is connected to the output terminal 58 at a high frequency.

The output terminal 5 7 is DC 3 V via a resistor R 1 and an inductance L 1 that block high-frequency signals, while the output terminal 5 8 is a resistor R 2 and an inductance L that blocks high-frequency signals. DC grounded via 2 Capacitance C 1 is used to ground the DC 3 V terminal at high frequency. The membrane 29 is floated in a DC manner by the capacitor C 2, and a control voltage is applied to the control terminal 59 via a resistor R 3 and an inductance L 3 that cut off a high-frequency signal. Therefore, when 5 V is applied to the control terminal 5 9, the input terminal 5 6 is connected to the output terminal 5 8 in terms of high frequency, and when 0 V is applied to the control terminal 5 9, it is connected to the output terminal 5 7. The In the above eighth embodiment, the feature of the applied capacitive MEMS element is 2004/011219

 35 A single push-pull type capacitive MEMS device realizes a 1-input 2-output switching switch with low loss and significantly reduced off-line signal wrapping due to excellent off-state isolation characteristics can do.

 FIG. 14 is a block diagram for explaining the ninth embodiment.

This is an example of a high-frequency device equipped with a capacitive M EMS element of the present invention, which is a high-frequency filter module used for a mobile phone or the like.

 In FIG. 14, a high frequency filter 94 is disposed on a substrate 9 1, and an antenna 96, and a connection part 9 2 to a reception system and a connection part 93 to a transmission system are connected to the opposite side. The In this case, a switch is arranged at least in the front stage, the rear stage, or both the front and rear stages of the high frequency filter 94. As this switch, a switch based on the form shown in the seventh embodiment of the present invention or a form mounted with a switch based on the form shown in the sixth embodiment is used.

 By mounting the plurality of fills 94 and the capacitive M EMS element 95 of the present invention, the good switching characteristics of the present invention can be obtained. Reflecting this, signals of multiple frequency bands received from the antenna are switched and input to the desired connection path with low loss and low noise. Conversely, signals of multiple frequency bands are low loss and It is possible to output with low noise. Furthermore, there is an advantage that the wraparound of the output signal to the input signal side can be significantly reduced.

 The high-frequency filter and the capacitive MEMS element of the present invention are formed on the same substrate material as that of the filter, because the capacitive MEMS element of the present invention can be manufactured by any general semiconductor manufacturing technology. There is an advantage that it can be manufactured and made into one chip together with other passive elements.

Further, the equivalent circuit shown in the sixth embodiment and the seventh embodiment of the present invention. P2004 / 011219

 In the 36-line diagram, logic IC composed of active elements such as Si-MOFS FE T that transmits a control signal from the control terminal can be fabricated on the same substrate and made into one chip for the same reason as described above.

 That is, the capacitive M EMS element of the present invention can be manufactured on the same substrate using a general semiconductor manufacturing technique together with an active element and other passive elements.

 This makes it possible to provide a high-frequency device that is significantly smaller than when each element has been individually mounted on a mounting board.

 Due to the structure and properties of the capacitive MEMS element of the present invention, in addition to the use as a switch as described above, one or a plurality of this element can be connected and arranged in parallel and in series to provide an SP n T switch. Needless to say, the present invention can also be applied to variable capacity devices capable of changing the capacitance values in a wide range.

 FIG. 15 shows an example of the method for manufacturing the M E M S element of the present invention.

 Here, as an example, a manufacturing method of the capacitive M EMS element according to the first embodiment shown in FIG. 1 will be described. Other forms can be manufactured in accordance with this.

 On the insulating substrate 3, a lift-off two-layer resist pattern composed of an inverted pattern of the signal line 1 and the ground 2 is formed by using a photolithography technique. After this, using electron beam evaporation, deposit 0.05 μm of Ti on the first layer and 0.5 μm of Au (gold) on the second layer. . Then, unnecessary metal films and resists are removed using a known lift-off method to form a signal line 1 pattern and a ground 2 pattern ((a) in FIG. 15).

Subsequently, an alumina film having a thickness of 0.2 micrometers is applied to the sputtering method. PT / JP2004 / 011219

 37 After deposition, pattern formation is performed using the well-known Kiso lithography technology. Thereafter, the alumina film in the unmasked region is removed by etching, and the dielectric film 5 pattern is formed only in the desired region ((b) in FIG. 15).

 Next, using a well-known photolithography technique, a two-layer resist pattern for lift-off in which only a desired region on the signal line is opened is formed. After this, use electron beam evaporation to deposit a 0.05-micrometer-thickness meter T i on the first layer and a 0.2-micrometer thick Au (gold) on the second layer. . Then, unnecessary metal films and resists are removed by using a known lift-off method to form a pattern of the floating metal 6 having a desired shape ((c) in FIG. 15).

 Next, using a well-known photolithography technique, a two-layer resist pattern for lift-off in which only a desired region on the insulating substrate 3 is opened is formed. Thereafter, a high resistance film is deposited using an electron beam evaporation method. Then, by using a known lift-off method, unnecessary metal film and resist film are removed to form a resistance element 7 pattern having a desired shape ((d) in FIG. 15).

 Next, after forming a polyimide film on the entire surface of the insulating substrate 3 by spin coating, a sacrificial layer pattern made of a polyimide film in which only a desired region is opened by using a well-known photolithography technique and an etching technique 5 1 Form. The film thickness of the polyimide film was adjusted so that the film thickness after curing with high temperature baking was 1.2 micrometers ((e) in Fig. 15).

Next, an Au film having a thickness of 2.5 micrometers is deposited on the entire surface of the insulating substrate 3 by using a well-known electron beam evaporation method. After this, the membrane 8 is formed using the well-known photolithography technique and Ar + ion milling method. ((F) in Fig. 15). PT / JP2004 / 011219

 38 Finally, the sacrificial layer 51 is removed by chemical dry etching to complete the capacitive MEMS element of the present invention ((g) in FIG. 15).

 If it is difficult to fabricate the resistive element on the same substrate, a lead line pattern is formed from the floating metal, and the external resistive element or inductor element is formed at the element mounting stage. May be connected.

 In the example of the manufacturing method described above, an example in which the electron beam evaporation method is used for depositing various metal films has been shown. However, by using a sputtering method or the like, the surface flatness of the metal film is improved, Deviation of elements in the wafer can be reduced. In the above example, an example using a metal film mainly composed of A u is shown. However, the use of AI, Cu, or the like has an effect of reducing material costs.

 Although an example using the ion milling method has been shown for the processing of the above-mentioned membrane, a processing method most suitable for the metal material to be used, such as a chemical dry etching method, a wet etching method, and a lift-off method, can be used. It goes without saying that it is good.

 In the example of the manufacturing method described above, the film thickness of the membrane was 2.5 μm. However, as shown in the embodiment, it is preferable that the film thickness does not cause bending in each metal material, The optimum film thickness varies depending on the deposition method and is not particularly limited.

 In the case of the membrane, an example of using thick Au by electron beam evaporation was shown, but in addition to this, a thick Au film was formed on the thin Au film using electrolytic Au plating. Also good.

The material cost can be reduced by using the electrolytic Au plating method in which only a desired region is patterned by patterning with a photoresist or the like. In producing the membrane using the AU, in the manufacturing method, an example was shown in which only Au was deposited directly. However, in addition to titanium, several chromium, molybdenum, etc. were used as an adhesive layer with the adjacent layer. Adhesion can be improved by providing about nm to several tens of nm.

 The floating metal patterning, which is the main component of the present invention, has been described with respect to an example of patterning using the multilayer resist technique and the lift-off method. However, when other methods such as AI are used, Needless to say, chemical dry etching, etching, etc. may be used.

 Although an example in which an alumina film formed by sputtering is used as the dielectric film has been shown, other methods generally used in the normal semiconductor manufacturing process, such as a CVD method, may be used for the deposition method.

 As for the dielectric film material, any material can be applied as long as it is a solid material having at least an insulating property and a dielectric constant, such as an alumina film, a silicon oxide film, a silicon nitride film, and tantalum oxide. Further, a laminated film of these dielectric materials may be used instead of a single film. The larger the dielectric constant, the easier the device can be miniaturized and the better the electrical characteristics when the membrane is lowered.

 Although an example of using a standard polyimide film for the sacrificial layer 51 has been shown, if a photosensitive polyimide film is used, the process of applying a photoresist can be saved, thus simplifying the process. There is an advantage of being connected. In addition, if no problem such as heat resistance occurs, only a normal polyurethane may be used for the sacrificial layer.

The capacitive MEMS element of the present invention manufactured by the above manufacturing method is different from the conventional element in structure in that the area ratio of the floating metal in the opposing region is limited and the high-frequency signal is transmitted from the floating metal. PT / JP2004 / 011219

 It is to be connected in direct current to a substance having a desired potential through a substance that becomes resistance to No. 40. As far as the fabrication process is concerned, it is clear that the present invention has a great effect on the device characteristics with a small increase in the number of processes. That is, if the capacitive M E M S element of the present invention is manufactured according to the manufacturing method, a capacitive M E M S element having extremely good switching characteristics for a high frequency signal can be provided at a low price.

 The main embodiments of the present invention are listed below.

 (1) at least

 A substrate,

 An anchor formed on the substrate;

 A panel connected to the anchor;

 An upper electrode connected to the panel and elastically deforming the panel to move above the substrate;

 A lower electrode formed on the substrate, which is located below the upper electrode and has at least a region facing a part of the upper electrode;

 On the substrate on which the lower electrode is formed, a dielectric formed on a part of the lower electrode and a part of the substrate so as to cover at least a region wider than the upper electrode when viewed from the vertical direction of the substrate. Body membranes,

 A low-resistance metal film formed in contact with a part of the dielectric film located on the lower electrode and at least facing a part of the upper electrode;

When a DC voltage is applied between the upper electrode and the lower electrode, the upper electrode is attracted downward by the electrostatic force generated between the upper electrode and the lower electrode facing each other, and the upper electrode Part of the low resistance metal film is in contact with a part of the low resistance metal film, and the upper electrode and the low resistance metal film are electrically connected to each other before being connected via the low resistance metal film. 2004/011219

 41 In a capacitive MEM S element in which a capacitor structure comprising the upper electrode, the dielectric film, and the lower electrode is formed.

 A region in which the dielectric film and the low-resistance metal film are stacked on the lower electrode in a region where the upper electrode and the lower electrode face each other when viewed from the vertical direction of the substrate; The area where only the dielectric film is formed is mixed, and the area of the area where the dielectric film and the low-resistance metal film are stacked in the area where the upper electrode and the lower electrode face each other is as follows. A capacitive MEMS element characterized by being equal to or smaller than the area of the region where the dielectric film is exposed in the region.

 (2) at least

 A substrate,

 An anchor formed on the substrate;

 A panel connected to the anchor;

 An upper electrode connected to the panel and elastically deforming the panel to move above the substrate;

 A lower electrode formed on the substrate, having a region located below the upper electrode and facing at least a portion of the upper electrode;

 On the substrate on which the lower electrode is formed, a dielectric formed on a part of the lower electrode and a part of the substrate so as to cover at least a region wider than the upper electrode when viewed from the vertical direction of the substrate. Body membranes,

 A low-resistance metal film formed in contact with a part of the dielectric film located on the lower electrode and at least facing a part of the upper electrode;

When a DC voltage is applied between the upper electrode and the lower electrode, the upper electrode is attracted downward by the electrostatic force generated between the upper electrode and the lower electrode facing each other, and the upper electrode Part of the low The upper electrode connected via the low-resistance metal film by electrically connecting the upper electrode and the low-resistance metal film in contact with a part of the anti-metal film, and the dielectric In a capacitive MEMS element in which a capacitor structure composed of a body film and the lower electrode is formed,

 The capacitive M E M S element, wherein the low-resistance metal film is connected to a substance having a desired potential in a direct current manner through a substance that is resistant to a high-frequency signal.

 (3) The capacitive type according to item (2), wherein the substance that is resistant to the high-frequency signal is a substance that exhibits an electrical resistance value of at least 1 kΩ or more and less than 1 Ω. MEMS element.

 (4) In the above item (2), the substance that becomes a resistance to the high-frequency signal is an inductor that exhibits an impedance of at least 1 kΩ and less than 1 MΩ with respect to the high-frequency signal. The capacitive MEMS element described.

 (5) The capacitive MEMS element according to item (2), wherein the substance having the desired potential is the upper electrode.

 (6) The capacitive MEMMS device according to item (2), wherein the substance having the desired potential is the lower electrode.

 (7) The capacitive M E M S element according to item (2), wherein the substance having the desired potential is a ground region (earth).

 (8) The item described above, wherein the substance having the desired potential is a control electrode that controls a vertical movement of the upper electrode by applying a DC voltage.

Capacitance type M E M S element according to (2).

(9) In the item (1), the region where only the dielectric film according to claim 1 is formed is provided by an opening having a predetermined shape in the low-resistance metal film. The capacitive MEMS element described. 2004/011219

 43

(10) The capacitor according to (1), (2) above, wherein the panel, the anchor, and the upper electrode form an integral structure and are formed of a continuous metal body. Type MEMS element.

 (11) The capacitive MEMS element according to the item (8), wherein the metal body is a single-layer film containing at least aluminum, or a laminated film of an aluminum-containing film and another metal film. .

 (12) The capacitive MEMMS element according to the item (8), wherein the metal body is formed of a single layer film containing at least gold or a laminated film of a gold-containing film and another metal film.

 (13) The capacitive MEMMS device according to the item (8), wherein the metal body is formed of a single layer film containing at least copper or a laminated film of a copper-containing film and another metal film.

 (14) The item (1), (2), wherein the low-resistance metal film is composed of a single-layer film containing at least aluminum or a laminated film of an aluminum-containing film and another metal film. Capacitive MEMS element.

 (15) The item described above, wherein the low-resistance metal film comprises a single-layer film containing at least gold, or a laminated film of a gold-containing film and another metal film.

(1), Capacitance type M E M S element given in (2).

 (16) The low-resistance metal film is a single-layer film containing at least copper, or a laminated film of a copper-containing film and another metal film, The item (1), (2) Capacitive MEMS element.

 (17) From the item (1), the low-resistance metal film is a floating metal that is not connected to a high-frequency signal when no voltage is applied between the upper electrode and the lower electrode. 1 4) Capacitive MEMS device as described in 4).

(18) The capacitive MEMS device described in the items (1) to (15) is 11219

 44 A high-frequency device that is mounted on an on / off switch for high-frequency signals.

 (19) A high-frequency device characterized in that the capacitive MEMS element described in the items (1) to (15) is mounted on a high-frequency signal output switching switch.

 (20) A high-frequency device, wherein the capacitive MEMS element described in the items (1) to (15) is mounted on a high-frequency filter module for a mobile phone.

 (2 2) A high-frequency device, wherein the capacitive M E M S element described in the items (1) to (15) is mounted together with an active element on the same substrate.

 (2 3) A high-frequency device characterized in that the capacitive M E M S element described in the items (1) to (15) is mounted together with other passive elements on the same substrate.

 (2 4) At least

 A substrate,

 An anchor formed on the substrate;

 A panel connected to the anchor;

 An upper electrode connected to the panel and elastically deforming the panel to move above the substrate;

 A lower electrode formed on the substrate, having a region located below the upper electrode and facing at least a portion of the upper electrode;

 On the substrate on which the lower electrode is formed, a dielectric formed on a part of the lower electrode and a part of the substrate so as to cover at least a region wider than the upper electrode when viewed from the vertical direction of the substrate. Body membranes,

In contact with a part of the dielectric film located on the lower electrode, at least PT / JP2004 / 011219

 45 also includes a low-resistance metal film formed to face a part of the upper electrode,

 A region in which the dielectric film and the low-resistance metal film are stacked on the lower electrode in a region where the upper electrode and the lower electrode face each other when viewed from the vertical direction of the substrate; The area where only the dielectric film is formed is mixed, and the area of the area where the dielectric film and the low-resistance metal film are stacked in the area where the upper electrode and the lower electrode face each other is as follows. A method for manufacturing a capacitive MEMS element, characterized in that it is equal to or smaller than the area of the region where only the dielectric film in the region is formed,

 Forming the lower electrode pattern made of a metal film on the substrate;

 Forming a pattern made of a dielectric film at a desired position on the substrate including the upper surface of the lower electrode on the substrate on which the lower electrode is formed; and the lower electrode and the dielectric film on the substrate Forming a pattern made of the low-resistance metal film having a desired shape at a desired position in a region where the layers are stacked;

 Forming a pattern of a sacrificial film having a desired shape on the substrate on which the lower electrode, the dielectric film, and the low-resistance metal film are formed;

 Forming an anchor, the panel, and the upper electrode in an integrated structure by depositing and processing a metal film at a desired position on the substrate including the sacrificial film pattern;

 Capacitive type M E comprising a step of removing the sacrificial film

Manufacturing method of MS element. .

(25) The above item, characterized by comprising a step of forming a pattern made of a substance exhibiting a desired electric resistance value at a desired position on the substrate. P2004 / 011219

 46

(20) The method for producing a capacitive M E M S element according to (20).

 (2 6) The method for producing a capacitive M E M S element according to item (2), further comprising a step of forming an inductor having a desired impedance at a desired position on the substrate.

 The main symbols related to the drawings are as follows.

1 ... Signal line, 2 ... Ground, 3 ... Insulating substrate, 5 ... Dielectric film, 6 ... Floating metal, 7 ... Resistance element, 8 ... Memprene, 1 0 ... Anchor, 1 1 ... Panel, 1 2 ... Top Electrode,〗 3 ... Signal line, 1 4 ... Earth, 1 5 • ■ • Si substrate, 1 6 ... Cantilever, 1 7 ... Anchor, 1 8 ... Panel, 1 9 ... Top electrode, 2 0 ... Dielectric Body film, 2 1 ... Floating metal, 2 2 ... Resistive element, 2 4 ... Input signal line, 2 5 ... Output signal line on the left side, 2 6 ... Output signal line on the right side, 2 7 ... Ground, 2 8 ... Glass substrate 2 9 ... Membrane, 3 0 ... Anchor, 3 1 ... First spring, 3 2 ... Second spring, 3 3 ... Left upper electrode, 3 4 ... Right upper electrode, 3 5 ... Dielectric Membrane, 3 6… Left side floating metal, 3 7… Left side floating metal, 3 8… Left inductor element, 3 9… Right inductor element, 4 0… Input signal line, 4 1… Force signal line, 4 2 ... Earth, 4 3 Si substrate, 4 4 ... Membrane, 4 5 ... Anchor, 4 6 ... Panel, 4 7 ... Upper electrode, 4 8 ... Dielectric film, 4 9 ... Floating metal, 5 0 ... protrusion, 5 1 ... sacrificial layer, 5 2 ... high frequency switch, 5 3 ... input terminal, 5 4 ... output terminal, 5 5 ... control terminal, 5 6 ... input terminal, 5 7 ... left output terminal, 5 8 ... right output terminal, 5 9 ... control terminal, 6 0 ... glass substrate, 6 1 ... signal line, 6 2 ... ground, 6 3 ... control terminal, 6 4 ... mamprene, 6 5 ... anchor, 6 6 ... panel, 6 7— 1… Area for generating electrostatic force with earth 6 2, 6 7 — 2… Area in contact with floating metal, 6 7… Upper electrode, 6 9… Dielectric film, 7 0… Floating metal, 7 1 ... in Ductor element, 7 2 ... High frequency switch, 7 3 ... Input terminal, 7 4 ... Output terminal, 7 5 ... Control terminal, 9 1 ... Board, 9 2 ... Receiving system, 9 3 ... Transmission system, 9 4 ... High frequency filter 9 5 ... Capacitive MEMS element of the present invention, 9 6 ... Antenna Industrial applicability

The element of the present invention can be used as an electric signal switching element. In particular, it is useful for high-frequency signals, and a high-frequency device using the element can be provided. It is also possible to provide a method for manufacturing such an element.

Claims

The scope of the claims  1. Insulating substrate,  A lower electrode formed on the insulating substrate;  A dielectric layer formed on the lower electrode;  A conductor layer formed on the dielectric layer;  An upper electrode disposed opposite to the lower electrode and having a gap with at least a conductor layer on the dielectric layer, and for controlling contact / non-contact with the conductor layer on the dielectric layer; Have  The conductor layer on the dielectric layer is a conductor on the dielectric layer in a part of the facing area in a region where the upper electrode and the lower electrode face each other when viewed from the vertical direction of the insulating substrate. And an area of a region where the conductor layer on the dielectric layer is present in a region where the upper electrode and the lower electrode are opposed to each other on the dielectric layer in the opposite region. Capacitive MEMS element characterized by being equal to or smaller than the area of the area where the conductor layer does not exist. 2. Insulating substrate,  A lower electrode formed on the insulating substrate;  A dielectric layer formed on the lower electrode;  A conductor layer formed on the dielectric layer;  An upper electrode disposed opposite to the lower electrode and having a gap with at least a conductor layer on the dielectric layer, and for controlling contact / non-contact with the conductor layer on the dielectric layer; Have The capacitive MEMS device, wherein the conductor layer on the dielectric layer is connected to a desired potential in a direct current manner through a resistor for a high-frequency signal. 3. The capacitive M E M S element according to claim 2, wherein the resistor for the high-frequency signal is a substance exhibiting an electrical resistance value of at least〗 kΩ or more and less than 1 MΩ. 4. The capacitive M E M S element according to claim 2, wherein the resistor for the high-frequency signal is an inductor that exhibits an impedance of at least 1 and less than 1Ω to the high-frequency signal. 5. The desired potential is based on a direct current connection of the conductor layer on the dielectric layer to any one of the upper electrode, the lower electrode, the control electrode, and the ground region. Capacitive MEMS element.  6. The capacitive M E M S element according to claim 1, wherein the conductor layer on the dielectric layer has an opening.  7. The capacitive M MEMS device according to claim 1, wherein the conductor layer on the dielectric layer is a single layer film containing at least aluminum or a multi-layer metal laminated film containing an aluminum-containing film.  8. The capacitive M MEMS device according to claim 2, wherein the conductor layer on the dielectric layer is a single layer film containing at least aluminum or a multi-layer metal laminated film containing an aluminum-containing film.  9. The capacitive MEMS device according to claim 1, wherein the conductor layer on the dielectric layer is a single-layer film containing at least gold or a multi-layer metal laminated film containing a gold-containing film. .  10. The capacitive MEMS according to claim 2, wherein the conductor layer on the dielectric layer is a single-layer film including at least gold or a multi-layer metal laminated film including a gold-containing film. element. 1 1. The conductor layer on the dielectric layer is a single layer film containing at least copper, or a multilayer metal laminated film containing a copper-containing film. The capacitive MEMS element described in 1.  1. The capacitive MEMS device according to claim 2, wherein the conductor layer on the dielectric layer is a single layer film containing at least copper, or a multi-layer metal laminated film containing a copper-containing film. . 13. A low frequency ¾ε, wherein the capacitive M EMS element according to any one of claims 1 to 12 has an on / off switch of a high-frequency signal.  1. A high-frequency device, wherein the capacitive MEMS element according to any one of claims 1 to 12 has a high-frequency signal output switching switch.  15. A high-frequency device characterized in that the capacitive element according to any one of claims 1 to 12 has an S element in a high-frequency filter module for a mobile phone.  16. A high-frequency device, wherein the capacitive MEMS element according to any one of claims 1 to 12 and an active element, a passive element, or both are mounted on the same substrate.  1 7. Forming a lower electrode on an insulating substrate;  Forming a dielectric film at a desired position on the insulating substrate including the upper surface of the lower electrode;  Forming a conductor layer pattern at a desired position in a region where the lower electrode and the dielectric film are laminated on the insulating substrate;  Forming a sacrificial film on the insulating substrate on which the lower electrode, the dielectric film, and the low-resistance metal film are formed;  Forming an upper electrode on the insulating substrate including the sacrificial film at a position facing the lower electrode; A step of removing the sacrificial film, MS element manufacturing method <